A critical point separates We're Alive from other Zombie works. It has all of the things you expect, zombies, violence, destruction, moral ambiguity, so on and so forth.
I think the thing that makes it special is the optimism of the human spirit. In every other zombie story essentially we watch the last of society. Every last vestige of human morality is chipped away over the course of the story. In We're Alive despite everything we still see signs that the
characters believe that they can win. Right down to the final line of
season 3. We still have clear heroes and villains and not just because of different groupings but based on actions.
Michael will not be cutting off
Tardust's finger if he is ever captured (I
hope).
.
Zombie stories have always been about our paranoia about the end (I am thinking of Night of the Living Dead for this one) or a warning about some aspect of our culture like materialism (Dawn of the Dead respectively). We're alive is as the subtitle says a story of survival. Despite the odds being firmly against them I have to believe a remnant can and will survive. It is the optimism, humor, and hope that makes it different from everything else.